Bifurcation and Periodicity in Granular Soils: Implicationsto Geomechanics and Hazard Mitigation

该项目将构建一个内部，长度依赖的颗粒材料塑性理论，应用于不稳定现象的研究。将对这一概念进行分析、数值和实验评估，以确定这种方法是否能够提供有关变形不均匀性的增长和波长选择的信息。内部长度尺度将通过描述应力不对称性的coserat型修正或描述塑性流动规律非均质性的梯度相关项引入。这两种方法的优点和缺点将被检查和最简单的形式将被用来研究三类危险相关的问题：剪切带，表面不稳定性和液化。这项工作将使人们更好地了解物理破坏过程，这对于制定适当的缓解措施至关重要。

The project will construct an internal, length-dependent plastic theory for granular materials to be applied to the study of instability phenomena. Analytical, numerical and experimental evaluation of this concept will be conducted to determine the ability of this approach to provide information on the growth and wave length selection of the associated deformation inhomogeneities. The internal length scale will be introduced either through a Cosserat- type modification characterizing the assymetry of stress, or a gradient-dependent term characterizing the heterogeneity of the plastic flow-rule. The merits and drawbacks of both approaches will be examined and the simplest possible form will be used to study three classes of hazard-related problems: shear banding, surface instabilities, and liquefaction. This work will provide a better understanding of the physical failure processes which are fundamental for the development of appropriate mitigation measures.